Fingerprint sensing device and fingerprint sensing method

Abstract

A fingerprint sensing device includes a fingerprint sensor and a processor. The fingerprint sensor is configured to acquire a plurality of fingerprint reference frames. The processor is coupled to the fingerprint sensor. The processor is configured to superimpose the plurality of fingerprint reference frames. The processor analyzes the plurality of fingerprint reference frames to determine multiple first regions and multiple second regions of the plurality of fingerprint reference frames. The processor calculates multiple reference pixel values of the plurality of fingerprint reference frames according to multiple weight value functions to generate a superimposed fingerprint frame. The weight value functions corresponding to the first regions of the plurality of fingerprint reference frames are linearly changed.

What is claimed is: 
     
       1. A fingerprint sensing device, comprising:
 a fingerprint sensor, configured to acquire a plurality of fingerprint reference frames; and 
 a processor, coupled to the fingerprint sensor, configured to superimpose the fingerprint reference frames, 
 wherein the processor analyzes the fingerprint reference frames to determine a plurality of first regions and a plurality of second regions of the fingerprint reference frames, and the first regions of the fingerprint reference frames are located between the second regions of the fingerprint reference frames, 
 wherein the processor calculates a plurality of reference pixel values of the fingerprint reference frames according to a plurality of weight value functions to generate a superimposed fingerprint frame, 
 wherein the weight value functions corresponding to the first regions of the fingerprint reference frames are linearly changed, 
 wherein one of the weight value functions corresponding to a second region of one of the fingerprint reference frames has a maximum value, and the other weight value functions corresponding to the second regions of the other fingerprint reference frames have minimum values. 
 
     
     
       2. The fingerprint sensing device according to  claim 1 , wherein the fingerprint sensor acquires the fingerprint reference frames according to different exposure times. 
     
     
       3. The fingerprint sensing device according to  claim 1 , wherein the processor determines a quantity of the fingerprint reference frames acquired by the fingerprint sensor according to a dynamic range of an original fingerprint frame, and the dynamic range of the original fingerprint frame is inversely proportional to the quantity of the fingerprint reference frames. 
     
     
       4. The fingerprint sensing device according to  claim 1 , wherein a dynamic range of the superimposed fingerprint frame is higher than a dynamic range of each of the fingerprint reference frames. 
     
     
       5. The fingerprint sensing device according to  claim 1 , wherein the processor performs a weighted average calculation on each of the reference pixel values of the fingerprint reference frames according to the weight value functions to generate the superimposed fingerprint frame. 
     
     
       6. The fingerprint sensing device according to  claim 1 , wherein the weight value functions are one-dimensional functions. 
     
     
       7. The fingerprint sensing device according to  claim 1 , wherein the weight value functions are two-dimensional functions. 
     
     
       8. The fingerprint sensing device according to  claim 1 , wherein the second region of the one of the fingerprint reference frames has a highest contrast compared with the second regions corresponding to the other fingerprint reference frames. 
     
     
       9. The fingerprint sensing device according to  claim 1 , wherein each of the weight values corresponding to the weight value functions is within a range of 0 to 1. 
     
     
       10. A fingerprint sensing method, adapted to a fingerprint sensing device, wherein the fingerprint sensing device comprises a fingerprint sensor and a processor, the fingerprint sensing method comprising:
 acquiring a plurality of fingerprint reference frames by the fingerprint sensor; 
 analyzing the fingerprint reference frames to determine a plurality of first regions and a plurality of second regions of the fingerprint reference frames by the processor, wherein the first regions of the fingerprint reference frames are located between the second regions of the fingerprint reference frames; and 
 calculating a plurality of reference pixel values of the fingerprint reference frames according to a plurality of weight value functions by the processor to generate a superimposed fingerprint frame, 
 wherein the weight value functions corresponding to the first regions of the fingerprint reference frames are linearly changed, 
 wherein one of the weight value functions corresponding to a second region of one of the fingerprint reference frames has a maximum value, and the other weight value functions corresponding to the second regions of the other fingerprint reference frames have minimum values. 
 
     
     
       11. The fingerprint sensing method according to  claim 10 , wherein a step of acquiring the fingerprint reference frames by the fingerprint sensor comprises:
 acquiring the fingerprint reference frames based on different exposure times by the fingerprint sensor. 
 
     
     
       12. The fingerprint sensing method according to  claim 10 , wherein the step of acquiring the fingerprint reference frames by the fingerprint sensor comprises:
 determining a quantity of the fingerprint reference frames acquired by the fingerprint sensor according to a dynamic range of an original fingerprint frame by the processor, 
 wherein the dynamic range of the original fingerprint frame is inversely proportional to the quantity of the fingerprint reference frames. 
 
     
     
       13. The fingerprint sensing method according to  claim 10 , wherein a dynamic range of the superimposed fingerprint frame is higher than a dynamic range of each of the fingerprint reference frames. 
     
     
       14. The fingerprint sensing method according to  claim 10 , wherein a step of calculating the reference pixel values of the fingerprint reference frames according to the weight value functions by the processor to generate the superimposed fingerprint frame comprises:
 performing a weighted average calculation on each of the reference pixel values of the fingerprint reference frames according to the weight value functions to generate the superimposed fingerprint frame. 
 
     
     
       15. The fingerprint sensing method according to  claim 10 , wherein the weight value functions are one-dimensional functions. 
     
     
       16. The fingerprint sensing method according to  claim 10 , wherein the weight value functions are two-dimensional functions. 
     
     
       17. The fingerprint sensing method according to  claim 10 , wherein the second region of the one of the fingerprint reference frames has a highest contrast compared with the second regions corresponding to the other fingerprint reference frames. 
     
     
       18. The fingerprint sensing method according to  claim 10 , wherein each of the weight values corresponding to the weight value functions is within a range of 0 to 1.